PROJECT SUMMARY/ABSTRACT Hypertrophic cardiomyopathy (HCM) is a devastating inherited disease that is associated with high incidence of arrhythmia, conduction anomaly, and sudden cardiac death in the patients. Previous studies have revealed that heart muscle tissues of HCM patients exhibit disorganized heart muscle cells or cardiomyocytes, randomly organized sarcomere, and aberrant gap junction structure. Gap junction is a specialized structure that localizes preferentially at the longitudinal ends of mature cardiomyocytes to facilitate rapid and directional electrical conduction. In HCM, gap junction is altered and connexin 43 (Cx43), a major gap junction protein in cardiomyocytes, is randomly distributed along the plasma membrane. While genetic studies have implicated mutations in sarcomeric proteins such as ?-cardiac myosin heavy chain (MYH7) as etiology of HCM, it has been unclear how the sarcomeric disarray seen in the hearts of patients with MCH can induce disorganized cardiac gap junctions to result in clinical arrhythmia. I hypothesize that sarcomeric protein alignment plays an important role in Cx43 localization and alteration of sarcomeric alignment in HCM results in abnormal Cx43 distribution and increase arrhythmia. The goal of this study is to improve gap junction formation and reduce arrhythmogenesis in HCM by identifying the key mechanisms that link sarcomeric alignment to Cx43 localization. Specifically, I propose to build upon my expertise in bioengineering to 1) examine effects of modulating cell shape and cell-cell contact on sarcomeric protein alignment and Cx43 localization in normal human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and 2) investigate whether the MYH7 mutation-induce sarcomeric disarray and altered Cx43 localization in clinical HCM, can be modeled using MYH7 mutant hiPSC-CMs. The anticipated payoff of the proposed project will be an improved molecular understanding of arrhythmogenic mechanisms in HCM. These goals are significant because the proposed platform can be utilized to develop novel anti-arrhythmic therapeutics and further be expanded into other iPSC-CM-based applications. At the same time, the proposed research training plan will also provide valuable opportunities to advance my knowledge in stem cell biology and cardiac development, which will complement my existing expertise in bioengineering and aid my future goal of setting up an independent research group in cardiovascular medicine.